The lungs are vital for various functions such as metabolism, secretion of substances including mucus and surfactant, and filtering of undesirable materials. Their main function is gas exchange to enable blood oxygenation and removal of carbon dioxide. The lungs house pulmonary airways that consist of a network of continuously-branching tubes which become shorter, narrower, and more numerous as they penetrate deeper into the lungs. The trachea (windpipe) is the main access point to transport air to and from the lungs. The trachea then splits into the left and right primary bronchi (generation one airways), each of which subsequently divides into two secondary bronchi.
Delivery of therapeutic fluids, such as surfactant solutions, into lungs is a major strategy to treat various respiratory disorders. Instilled solutions form liquid plugs in lung airways, e.g. in the trachea or primary bronchi. The plugs propagate downstream in airways by inspired air or forced ventilation, continuously split at airway bifurcations to smaller daughter plugs and simultaneously lose mass from their trailing menisci, and eventually rupture. A uniform distribution of the instilled liquid in lung airways is essential for increasing the treatments success. The uniformity of distribution of instilled liquid in the lungs greatly depends on the splitting of liquid plugs between daughter airways, especially in the first few generations of airways from which airways of different lobes of lungs emerge.
U.S. Pub. No. 2011/0093243 discloses creating a computational fluid dynamics mesh. A set of images is obtained, representing the branching biological structure, such as airways within a lung. The center line locations and measurements of airway diameter from the images, including estimated diameters for the one dimensionally modeled airways, is used to create an initial estimation of a branching mesh. Aspects of the image are analyzed to extract information defining one or more surfaces. Branching passageways can be determined in part with reference to structures that can be discerned and in part are inferred from predetermined relationships forming a model. Notably, the mesh is only provided for computational fluid dynamic (CFD) analysis and the '243 publication appears to lack the ability to produce a 3D object.
There remains a need in the art for rational design of improved lung airway models in order to help elucidate delivery conditions that improve uniformity of distribution of instilled therapeutic liquids, such as surfactants, in the lungs. Availability of model airway trees is essential for progress in this area.